1. Field of the Invention
This invention relates generally to transportation, and more particularly to the construction of wheels for wheeled vehicles.
2. General Background and State of the Art
Related co-owned U.S. Pat. No. 6,375,243 and U.S. patent application Ser. No. 10/061,012 disclose substantial design advances and enhancements (which will be referred to herein as the “Enhanced Design”) over the current technology for roller coaster load wheels. FIGS. 1 and 2 of the present application illustrate the details of the Enhanced Design. These enhancements are made possible by a double-layer tire construction with separate inner member 220 and outer tire member 210, outer tire member 210 being made of a relatively hard and rigid material while inner tire member 220 is made of a relatively softer and more resilient material. The tire members are mounted on two hub members 230 and 240 which mechanically secure tire members 210 and 220 when hub members 230 and 240 are attached to each other with bolts 270. The Enhanced Design provides longer wear than prior art wheels because of the durability of outer tire member 210, without sacrificing the desired ride quality. Because tire members 210 and 220 are not bonded to hub members 230 and 240, and because the hub assembly is a “split-hub” construction rather than a single piece construction, repair and replacement of wheels can be made more quickly and easily with the Enhanced Design than wheels constructed in accordance with the current technology used in making wheels for rides. Hub members 230 and 240 also include openings 236 in them to allow for circulation of air for cooling of the wheels during operation, thus helping to alleviate problems associated with heat buildup, especially in tires used under extremely high loads.
The present invention builds upon the Enhanced Design wheel assemblies, while providing further benefits and advantages over the prior art as well as the Enhanced Design. For example, the Enhanced Design incorporates two distinctively different hub member configurations, thus meaning that for each wheel assembly, operators have to ensure that they stock quantities of both hub members. This feature also requires fabricators to have separate sets of tooling for the hub members in order to be able to produce the hub assemblies.
The Enhanced Design is configured for use with the dual layer tire design and can not be easily used for other wheel configurations that are used on wheeled vehicles.
In the Enhanced Design, the bolts connecting the two hub members must be inserted through the inboard hub member (the member closest to the ride vehicle body), thus adding some difficulty to the maintenance and changing of wheels.
In the Enhanced Design, one hub member (the inboard member) has to carry the bearings, while the other hub member does not, thus requiring that the hub members are of different construction.
In the Enhanced Design, the hub members are cast and designed for use in applications where heat removal is an issue and does not allow for using less expensive machined hubs that can be used in applications where heat removal is not an issue.